1. Technical Field of the Invention
The present invention relates to engine control devices and engine control systems and, more particularly, to an internal combustion engine control device and an internal combustion engine control system applied to an internal combustion engine having recirculation means for recirculating a part of exhaust gases from an exhaust gas passage to an air-intake passage.
2. Description of the Related Art
In the related art, there has been known an EGR system arranged to recirculate a part of exhaust gases from an exhaust gas passage to an air-intake passage for thereby achieving a reduction in a NOx component of exhaust gases as disclosed in Japanese Patent Application Publication No. H09-53519.
With the EGR system of such a structure, under a circumstance where a vehicle, carrying an internal combustion engines is running in, for instance, high altitudes (at a height of, for instance, 1000 m above sea level), a surrounding atmospheric pressure decreases with a resultant decrease in a mass flow rate of intake air drawn into a cylinder. This results in a decrease in the amount of oxygen intake air and, hence, the EGR system is compelled to reduce a recirculation rate (hereinafter referred to as “EGR amount”) for the purpose of obtaining a stabilized combusting state. This results in a difficulty of adequately exhibiting a favorable NOx eliminating effect.